Not Applicable.
Not Applicable.
1. Field of Invention
The present invention is directed generally to position location systems and methods.
2. Description of the Background
There are a number of position location systems well suited for applications that require the determination of a position location in an outdoor environment. However, because position location systems vary considerably in terms of accuracy, size, complexity, cost, and ease of use, many of these systems have shortcomings when used to determine position locations situated in an indoor environment. For example, global positioning systems (GPS), magnetic compass systems, and inertial navigation systems each have shortcomings when used for applications requiring the determination of a position location in an indoor environment.
Global positioning systems rely on modulated carrier signals transmitted from GPS satellites and received by a GPS receiver to determine position location. Information that is decoded to determine position location is carried by modulation signals that are mixed with two carrier signals. The two carrier signals, commonly known as L1 and L2, are transmitted at frequencies that are not particularly effective at passing through the exterior shell of a building. If no signal is received at the GPS receiver, the global positioning system is unable to determine position location. Therefore, global positioning systems are ill-suited for determining position locations in an indoor environment due to the attenuating effect that the exterior shell of the building has on the carrier signals.
Magnetic compass systems rely on a magnetic compass to indicate a direction of movement of an object. From the direction of indicated movement, a new position location relative to a previous position location can be determined. However, when used to determine position location in an indoor environment, magnetic compass systems are susceptible to inaccuracies resulting from a biasing effect that magnetic material in the building may have on the compass. For buildings constructed with structural steel members, the inaccuracies of the magnetic compass system can be very pronounced.
Although inertial navigation systems may be built to determine an accurate indoor position location, inertial navigation systems generally incorporate a large number of mechanical components, such as accelerometers and gyroscopes, thereby tending to cause inertial navigation systems to be relatively bulky, unwieldy, and expensive.
Thus, there exists a need for a position location system that overcomes the limitations, shortcomings, and disadvantages of known position location systems.
The present invention is directed to a system for determining a position of a user. According to one embodiment, the system includes a distance sensor in communication with a position tracking device. The distance sensor is for detecting movement by the user, and the position tracking device is for determining the position of the user based on detection of movement by the user and a relative change in direction input from the user.
According to another embodiment, the system includes: a distance sensor for detecting movement by the user; an input device for allowing the user to enter a relative change in direction input; a position tracking module in communication with the distance sensor and the input device for determining the position of the user based on detection of the movement by the user and the relative change in direction input; and an output device in communication with the position tracking module for displaying the position of the user. According to another embodiment, the system may additionally include a radio receiver and a radio coverage mapping module in communication with the radio receiver and the position tracking module.
According to yet another embodiment, the present invention is directed to a method for determining a position of a user. The method includes receiving a relative change in direction input from the user via a graphical user interface, determining a distance traversed by the user, determining the position of the user based on the relative change in direction input from the user and the distance traversed by the user, and displaying the position of the user via the graphical user interface.
The present invention, in contrast to prior art position location systems, provides an efficient, inexpensive, and relatively accurate technique for determining and tracking the position of a user. In addition, unlike many prior art position location systems, the techniques of the present invention are operable in indoor environments. Consequently, the present invention may be used advantageously, for example, by wireless local access network (WLAN) designers in determining the appropriate positions for access points of the network.